飢餓素(ghrelin)是一種由28個胺基酸所組成的多胜肽激素，其可透過生長激素分泌接受器(growth hormone secretagogue receptor, GHSR)，而具有強力刺激生長激素分泌的作用。此外，越來越多的研究也顯示飢餓素在進食行為及能量的恆定方面亦扮演重要的角色。雖然飢餓素是在下視丘被發現的，但是循環中大多數的飢餓素卻是由胃部所分泌。目前已有許多因子被證實可以影響飢餓素，例如：進食、睡眠、日夜節律、體重、生殖激素，以及還可能包括運動。運動和飢餓素一樣都可以刺激生長激素的分泌，不過研究指出運動中飢餓素濃度並未隨著生長激素上升，顯示運動所誘發的生長激素增加並非經由飢餓素所引起的。另外，長期運動所引起的體重下降，已經被觀察到同時也伴隨有空腹時飢餓素濃度增加的現象，不過，在單次運動對飢餓素濃度影響的研究結果則不一致，有些認為沒有改變，有些則是在運動後顯著下降，這些矛盾仍需要未來更多的研究加以釐清。

Ghrelin, a 28-amino-acid peptide, is the endogenous ligand for the growth hormone secretagogue receptor (GHSR) and potently stimulates growth hormone (GH) release. In addition, there is increasing evidences to show that ghrelin acts as a key role in regulating food intake and energy homeostasis. Although the ghrelin is found in the hypothalamus, most circulating ghrelin is secreted from the stomach. Ghrelin would be affected by many factors: for instance, food intake, sleep, body weight, diurnal rhythm, reproduction hormone and perhaps exercise. Exercise also is a well-known stimulator of GH secretion as ghrelin, but is not observed with significant increase in plasma ghrelin levels. It means that ghrelin is not the stimulator in the exercise-induced stimulation of GH release. Besides, weight loss by long-term exercise is associated with an increase in fasting plasma ghrelin levels. In contrast, previous research has given contradictory results, showing either an unchanged or decreased ghrelin levels after an acute exercise. Further studies are needed to fully elucidate this contradiction.

運動; 飢餓素; 生長激素

Exercise; Ghrelin; Growth hormone